Patent NZ-196469-A (NZ)
Title: Electric fence: pulse generator and power saving with full discharge when animal touches fence condutor
Inventor: WEINREICH W
IPC: H05C1/04
Filed: 1981-03-11
Abstract: 1. A pulse generator, particularly for generating cattle-fence pulses, a) comprising a pulse transformer to the primary winding (W1 ) of which an electric charging capacitor (C1 ) and to the secondary winding (W2 ) of which an electric capacitor (Cz ; C2 + Cz ), for example an electrified fence which has an electric capacity, are connected, the electric capacity of the charging capacitor (C1 ) being considerably greater than the electric capacity of the capacitor (Cz ; C2 + Cz ) connected to the secondary side, the charging capacitor (C1 ) being constantly connected to a charging circuit (G1 ; G2 ) and, in the parallel circuit of charging capacitor (C1 ) and primary winding (W1 ) of the pulse transformer, a thyristor (Th), which is controlled by means of a pulse timer (T) for firing in a previously determined sequence in time, or a transistor which is provided with an external control arrangement, being inserted as a switch for generating an oscillation ; b) by corresponding development of the circuit arrangement and its electric components in the equivalent circuit, the inductance (L) and the leakage inductance (Ls) of the pulse transformer forming a coupled series- and parallel-tuned circuit with the capacities of the electric capacitors connected to the primary and secondary side of the pulse transformer, the series-tuned circuit of which coupled series-and parallel-tuned circuit contains the leakage inductance (Ls), the capacity which is effective at the secondary side, and resistive impedances, the electric values of which are given by the electric magnitudes of the pulse transformer and of the connected capacitors (C1 , C2 , Cz ), in which arrangement the closing of the switch in the parallel circuit of charging capacitor (C1 ) and primary winding (W1 ) of the pulse transformer and the discharge current which thus begins to flow are also accompanied by a transient event with a first sinusoidal transient current which flows via the series-tuned circuit and the switch and the frequency of which is determined by the leakage inductance (Ls) and the electric capacity which is effective in the series-tuned circuit and the damping of which is determined by the resistive impedances which are effective at the series-tuned circuit and, for the purpose of opening the parallel circuit consisting of charging capacitor (C1 ) and primary winding (W1 ) of the pulse transformer c.a) during operation without bypassing energy in the secondary circuit the transient event is used, in order to prevent energy losses, for cutting off the thyristor (Th) or transistor, with the charging capacitor (C1 ) being only partially discharged, whereas c.b) during operation including bypassing of energy in the secondary circuit, an increased damping, produced by adding a resistance (Rz ) of previously determined limit size on the secondary side, and the consequent adequate suppression of the negative half-wave (between pi 1 and 2pi 1 ) of the transient current is used for stopping the cutting-off of the thyristor or transistor by means of the transient event until the charging capacitor (C1 ) has been completely discharged, characterised in that the thyristor (Th) turn-off time and the pulse timer (T) firing pulse width or the phase relationships, which are analogous to the thyristor turn-off time and to the firing pulse width, of the signals supplied by the external-control arrangement to the transistor, are tuned to the electric values, determining the frequency of the transient event, of leakage inductance (Ls), capacity effective on the secondary side and resistive series impedance (R), in order to meet the following conditions : - that the triggering firing pulse, which makes the thyristor (Th) or transistor conductive, is shorter than the first positive half-wave (between O and pi 1 ) of the sinusoidal transient current, - that the thyristor or transistor, during a fully formed negative half-wave (between pi 1 and 2pi 1) of the sinusoidal transient current is cut off for the duration of this half-wave and - that, with the presence of a damping of previously determined magnitude in the series-tuned circuit, the negative half-wave (between pi 1 and 2pi 1 ), caused by this and at least partially suppressed, of the sinusoidal transient current is insufficient for the thyristor (Th) or transistor to be cut off or held in a cut-off state.